Jet mixing in preparation of monodisperse silver halide emulsions

Claim 1

A process for preparing a photographic emulsion having a controlled silver halide grain size, structure, and size distribution, which comprises the steps of: (1) charging a precipation vessel with an aqueous solution of gelatin, (2) cycling a portion of said aqueous solution of gelatin through a first line, adding silver nitrate thereto to form a first stream, and returing said stream to said precipitation vessel, (3) simultaneously cycling another portion of said aqueous solution of gelatin through a second line, adding an alkali metal halide or mixed halide solution thereto to form a second stream, and returning said second stream to said precipitation vessel, (4) mixing both streams in said vessel to precipitate silver halide grains therein, (5) recycling the contents of said precipitation vessel into said first and second stream, and thence back into the precipitation vessel, whereby additional silver halide is precipitated on the initially precipitated grains to form silver halide grains of controlled structure, size and size distribution, characterized in that all of the aforesaid streams are introduced into the precipitation vessel in the form of high velocity downwardly directed jets positioned in close proximity to each other and which terminate below the liquid level in the vessel, whereby the recycled streams are uniformly mixed in a defined region and silver halide grains are precipitated at uniform pAg.